The present invention relates to radar array systems, and more particularly to radar arrays mounted on rotating array platforms.
Arrays such as RF beam scanning arrays and the like are often implemented using large rotating array platforms that revolve the array in the azimuth direction. For example, the platform may rotate so as to slew the array by a predetermined azimuth angle, or to scan the entire range of azimuth angles available to the antenna at a constant angular rate. Traditional approaches to implementing rotating radar array platforms involve the use of a variety of mechanical or electromechanical parts including sliprings for providing array power, and large load-bearing bearings to support the rotating platform. However, these components are subject to significant stress, resulting in mechanical fatigue and ultimately component failure. This of course impacts on the reliability of the platform and overall, on the revolving radar antenna system.
Sliprings are a limiting feature in revolving antenna designs. Commercially available sliprings have limited current transmission capability. This limits the power that can be supplied to a conventional radar array. Future radar arrays may require 1000 amps or more, and may not be adequately supported using sliprings.
Fluid cooling presents another limitation on conventional arrays. Coolant has conventionally been transmitted to radar arrays using a rotary fluid joints, which have a tendency to leak.
An apparatus and method for providing a reliable rotating array that is not subject to such component fatigue is highly desired.
One aspect of the invention is a position sensing system for a radar array. A marker is located on a portion of an array assembly. The array assembly includes a radar array that rotates about an axis normal to a radiating face of the radar array during operation. An optical sensor detects the marker to sense an angular position of the radar array.
Another aspect of the invention is a method for sensing a position of a radar array, comprising the steps of: rotating an array assembly that includes a radar array about an axis normal to a radiating face of the radar array during operation; and reading a marker located on a portion of the array assembly to sense an angular position of the radar array.